p. 28 – History of Evolutionary Thought

Early Ideas On Earth’s Organisms Aristotle was a Greek philosopher who believed every species was designed for a purpose. Organisms were not that way by chance.

He classified organisms according to their complexity, with plants as the least complex and humans as the most.

Early Ideas On Earth’s Organisms Linnaeus was the 1st to group similar organisms and assign them Latin names. Two-word name: Genus & Species Naming system known as binomial nomenclature. Our name: Homo sapiens (wise person)

Malthus – publishes “An Essay on the Principle of Population,” where he theorized that a growing population would eventually outgrow all of their resources. The carrying capacity of a population is determined by limited resources.

Theories of Geologic Change Hutton – Theory of Gradualism: the idea that landforms were shaped by very slow changes over a long period of time, and not by natural disasters.

His work supported the idea of extinction. Cuvier – studied mammoth fossils and discovered that their bones were different when compared to living elephants. His work supported the idea of extinction. Theory of Catastrophism: past natural disasters shaped landforms, and caused species to become extinct in the process. :

Lyell – Theory of Uniformitarianism: the idea that the same processes that shaped landforms in the past also shape landforms today. Geologic processes that shape Earth are uniform, or the same, through time

Charles Lyell Proposed that the Earth was millions of years old instead of a few thousand years old

Timeline You’re going to make a timeline for the History of Evolutionary Theory. Lay paper sideways. Draw a horizontal line. Include the year, scientist’s name, & summary of their contribution.

Add to Table of Contents: p. 29 – Natural Selection

Jean–Baptiste Lamarck’s Theory of Evolution Lamarck was one of the first scientists to understand that change occurs over time. He proposed that all organisms evolve toward perfection and complexity.

Lamarck’s Theory of Use and Disuse If a body part were used, it got bigger and stronger. For example: Lamarck thought that the long necks of giraffes evolved as generations of giraffes stretched for higher leaves in the trees. If a body part was NOT used, it then became smaller and weaker.

Jean–Baptiste Lamarck Stated that changes in environment caused an organism’s behavior to change. This change led to greater use or disuse of a structure or organ, and the structure would become larger or smaller as a result. These acquired changes were passed on to offspring. Over time this led to new species!!

Lamarck’s Theory of Inheritance of Acquired Characteristics Proposed that by selective use and disuse of organs, organisms acquired or lost certain traits during their lifetime These traits were then passed on to their offspring, which ultimately led to the formation of new species!

Lamarck’s Mistakes Lamarck did NOT know how traits were inherited We now know traits are passed through genes Genes are NOT changed by activities in life Change through gene mutation occurs before an organism is born!

Contributor’s to Darwin’s thinking included: John-Baptiste Lamarck – Inheritance of Acquired Characteristics and Law of Use and Disuse Alfred Russel Wallace – organisms evolved from common ancestors

Wallace Arrived at the same conclusion as Darwin – that organisms had evolved from common ancestors. Evolution was driven by natural selection.

To understand natural selection, imagine a population of beetles: There is variation in traits. There is differential reproduction. There is heredity. End result:

Natural Selection Individuals in a population that have inherited beneficial adaptations produce more offspring than do other individuals in the same population.

Timeline Rough Draft Also Include: 1859 – Darwin publishes On the Origin of Species 1865 – Mendel publishes his experiments on heredity 1943 – Avery demonstrates that DNA is the genetic material

Evolutionary Timeline